06' 250 XC not quite running up to par

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It is not wanting to fully rev out on the top end. I suspected reeds and had a look, one has a slight gap (less than 1/16"). tried flipping it over to no avail. dealer says replacement reeds won't be in until late august (&%$#@!?). I am not 100% certain this is the issue.

It also seems to have more vibration than normal. the pipe definitely has a significant vibration about mid throttle. I can not determine the cause.

I thought the bike was running lean and jetted it with 40 pilot, 170 main, and needle (stock) 4th clip, but this seemed to make it worse so put it back to stock jetting of 35 pilot, 165 main, and 4th clip (this is what the manual specifies for my current elevation and temperature). runs better but still seems a bit off.

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the reeds work mainly in the low to mid range, wide o pen is not reed related. The reeds may need to be replaced but it doesnt sound like your problem.

You didnt say if you just got the bike or if it used to run way better and now it doesnt. Did you recemtly do some work to it?? Need more info here.

Generally a KTM is too rich on the needle and needs to have a replacement needle to run right. Get the right needle and I think your problem is solved.

The other possibility is the Power Valve system. On the newer bikes, 300 for sure, there have been many the a pressed in pin comes loose and falls out. This then prevents the PV from opening and the bike wont rev out n go. There are lots of threads on this at KTM talk . com.

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have a look inside your pipe,my 07 250 exc started doing the same thing today.just wouldnt come on the pipe or rev out.I pulled the pipe and found a large piece of meatal rattling around in there blocking the flow.I think the pipe is double skinned and a piece has broken off?

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If the bike was runnig good over the winter and into the spring and is now runnig poorly I'd first look at jetting and guess that the temps got warmer and you need to go leaner on the jetting. On my 07 250xc I jet 2 elevations or temp ranges leaner than I am riding at and it seems to jet pretty close (just a touch of smoke) Especially since you had worse running when you went richer on the jetting.

Second I'd look at the packing on the mufler.

And the newer needles seem much better than the NOZ.... Needles were. the newer N3.C series needles seem to have done away with the rich low rpm issue. If you are still using a NOZ needle I'd switch to the newer series.